High voltage switching power supplies utilize multiple PCBs for both control circuits and power generation circuits. Board circuit traces and the components mounted on the circuit board are under high voltage stress due to high voltage fields. Therefore, grounding design for high voltage PCBs is always a challenging task. More particularly, high power devices are highly integrated where high density components are mounted on limited board space. In addition, multiple PCBs are mounted within close proximity to each other with little board space clearance and with little clearance to the surrounding walls of the device enclosure.
For example, a 15 kV RMS high voltage source within an instrument case for measuring a high power utility device often has limited space clearance, which may pose a safety concern. A traditional solution would be to mount or support the high voltage source on long insulators, or to submerge the high voltage source in a liquid insulator, or use potting material. This solution, however, is not practical, since there is not enough space to use adequately long insulators. In addition, weight restrictions prevent using liquid or solid encapsulates to insulate the high voltage source.